Thanks for the info, I knew you had an air dryer from old posts, but your last post on it was a long time ago so I assumed that you had installed it by now. Based on this statement "My limited understanding is in very cold conditions both may be needed" I guess I am less inclined to install an air dryer. I also live in the actual Midwest, and probably the reason the FLU farm gets away with no alcohol is that we have really low humidity especially in the winter. I saw that EI has a replacement alcohol injector for $211 which seems steep for what it is. I have not been able to find any kind of kit so that I could repair the one I have. I wonder if I could just find sufficient "O" rings to get it to seal properly? I think my next step is to disassemble it and use my calipers to look for replacement "O" rings to see if that will do the trick.I still havent made the conversion to an air dryer but have all the major parts but have not spent the time to get all the adapter fittings for the piping. My newer 1300 series ex German military came stock with an air dryer but I think it still has an alcohol injector. My limited unstanding is in very cold conditions both may be needed. As long as the unit meets the pressure rating any alcohol injector can work on the system but the nice thing with the SEE design is its got a built in bypass valve for non freezing conditions. Atkinson & Vos sells alcohol injectors that sort of look like the SEE unit but not identical.
I have received feedback that a downside for installing an air dryer in place of alcohol injector is that the distance from the engine air compressor and the air dryer is far shorter than on the 1300. This could lead to exceeding the temperature rating of the desiccant media. I haven't checked if its an issue in my climate but I doubt it.
As to if you need to dry air it really depends on the temps you are working in and the weather conditions. I you follow the ops procedures and drain the air tanks after use and see water coming out, it means that there is water in the system that would have frozen overnight if you hand not drained it. My guess is the most likely spot for a freeze up is the air regulator valve. Its a low point on the system. It does blow off air on occasion so that will keep large volumes of water out of it. Once the air leaves the regulator its going to cool quickly and condense into liquid and end up in the air tanks. Once it starts freezing in the tanks I do not think its going to thaw on its own if the temps stay cold.
Thanks again for your help.